From patchwork Wed Dec 4 21:36:02 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Hubbard X-Patchwork-Id: 11273633 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C47C5138C for ; Wed, 4 Dec 2019 21:36:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A2037206DF for ; Wed, 4 Dec 2019 21:36:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="eCFl7oV6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728030AbfLDVgG (ORCPT ); Wed, 4 Dec 2019 16:36:06 -0500 Received: from hqnvemgate25.nvidia.com ([216.228.121.64]:3151 "EHLO hqnvemgate25.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728011AbfLDVgF (ORCPT ); Wed, 4 Dec 2019 16:36:05 -0500 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate25.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Wed, 04 Dec 2019 13:36:01 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Wed, 04 Dec 2019 13:36:05 -0800 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Wed, 04 Dec 2019 13:36:05 -0800 Received: from HQMAIL105.nvidia.com (172.20.187.12) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Wed, 4 Dec 2019 21:36:04 +0000 Received: from hqnvemgw03.nvidia.com (10.124.88.68) by HQMAIL105.nvidia.com (172.20.187.12) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Wed, 4 Dec 2019 21:36:04 +0000 Received: from blueforge.nvidia.com (Not Verified[10.110.48.28]) by hqnvemgw03.nvidia.com with Trustwave SEG (v7,5,8,10121) id ; Wed, 04 Dec 2019 13:36:04 -0800 From: John Hubbard To: Andrew Morton , Jason Gunthorpe , Leon Romanovsky , Christoph Hellwig CC: Ira Weiny , , , LKML , John Hubbard , Christoph Hellwig Subject: [PATCH v2 1/2] mm/gup: allow FOLL_FORCE for get_user_pages_fast() Date: Wed, 4 Dec 2019 13:36:02 -0800 Message-ID: <20191204213603.464373-2-jhubbard@nvidia.com> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191204213603.464373-1-jhubbard@nvidia.com> References: <20191204213603.464373-1-jhubbard@nvidia.com> MIME-Version: 1.0 X-NVConfidentiality: public DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1575495361; bh=D5FKf6o88yrnam68mO83xEuXphYTA3McnnbS0GFu5aA=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:X-NVConfidentiality: Content-Transfer-Encoding:Content-Type; b=eCFl7oV6N1zFHWhmaXu9MCkZmrub7KXbOYWLH/D/jUkygF0DtjswPT2qe+aARAZFH jalNYGfDUmDPJZcLuaNkfZQs5g8cxMa8gn/wgOSGkjteGuJH6rxi6NZuRw1Vlaqb2E 7uzMo7yCYyx1ZuotG2ThIsFANYlKuS2hdorpsuhz/r8JOAo/QWLOsWH+ytGPxUtk/8 Ge1jG58RtT9eRllOlBhF4qIJXXoZlK8xvAZ47WoMzWeGx9KoUM3NYZ65MgiySrtka4 w41lEaiz0oliyAhaKRxPeLlCM2bWfLxMhWhwnoW+cxAjJU3TqbQlXWqq9wKural0c/ P45ahLYmbnzlA== Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org Commit 817be129e6f2 ("mm: validate get_user_pages_fast flags") allowed only FOLL_WRITE and FOLL_LONGTERM to be passed to get_user_pages_fast(). This, combined with the fact that get_user_pages_fast() falls back to "slow gup", which *does* accept FOLL_FORCE, leads to an odd situation: if you need FOLL_FORCE, you cannot call get_user_pages_fast(). There does not appear to be any reason for filtering out FOLL_FORCE. There is nothing in the _fast() implementation that requires that we avoid writing to the pages. So it appears to have been an oversight. Fix by allowing FOLL_FORCE to be set for get_user_pages_fast(). Fixes: 817be129e6f2 ("mm: validate get_user_pages_fast flags") Cc: Christoph Hellwig Signed-off-by: John Hubbard Reviewed-by: Leon Romanovsky --- mm/gup.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/gup.c b/mm/gup.c index 7646bf993b25..5244b8090440 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -2415,7 +2415,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, unsigned long addr, len, end; int nr = 0, ret = 0; - if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM))) + if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM | + FOLL_FORCE))) return -EINVAL; start = untagged_addr(start) & PAGE_MASK;